There is an ever-increasing need for stronger and more durable power transmission belts including notably V-belts to satisfy the complex needs of industry. The range of application of V-belts for transmitting power is constantly expanding between the extremes of very small radius drives to heavy power transmission applications.
To meet these expanding needs, it has been proposed in the prior art to strengthen V-belts and other transmission belts by incorporating therein various arrangements of textile reinforcements and, in some cases, metal cable reinforcements including twisted strand steel cables. These efforts to strengthen transmission belts have been in conjunction with the use of improved elastomers having high tensile strength characteristics and resistance to fretting, cracking and corrosion.
Notwithstanding these efforts, the need and demand for improved flexible transmission belts persists in the art, and it is therefore the objective of this invention to satisfy this need to a substantial extent through the provision of a steel cord belt reinforced power transmission belt of increased flexibility, stability, tensile strength, resistance to twisting or kinking, and also resistance to cracking. In accordance with the invention, all of these improved characteristics are provided in an economic manner and in an entirely practical manner by utilizing a highly flexible and high strength steel cord belt reinforcement in one or more layers internally within the transmission belt, with such layer or layers parallel to the inner and outer parallel surfaces of the transmission belt. The formation and bonding of the steel cord belt reinforcement is accomplished by known techniques currently in wide usage by tire manufacturers in connection with the very popular steel cord belted automotive tires now on the market.
Some examples of the patented prior art which fall short of accomplishing the objectives of this invention but which are of interest in showing the field of the invention are U.S. Pat. Nos. 3,221,869, Paasche; 3,479,892, Cicognani; and 3,736,805, Dent.
Another vital factor in satisfactory V-belt service is freedom from the necessity for frequent adjustment of belt tension caused by stretching. The invention also satisfies this need of the art by providing a belt having a nearly zero stretch factor. This is made possible by employing high-tensile steel strands or cords in a thin single layer woven screen-like internal steel belt, to be fully described. Such a belt has practically zero stretch and great resistance to shock loading and requires practically no tension adjustment after installation. By employing several steel cord belts at strategic zones of the V-belt, the overall belt strength can be made exceptional, to meet the needs of heavier loads at higher speeds for longer periods of time in comparison to conventional belts, thus greatly increasing the safety factor.
In applications which require more than one V-belt for transmitting the load, the use of the invention can significantly reduce the number of belts required, without loss of strength in the drive.
By means of the invention, V-belt tension in a particular application can be made more uniform, with the result of much longer belt life. The ideal tension is that which will assure no belt slippage under optimum loading. If the tension is too high, the life of the belt will decrease and bearing and other machine stresses will be excessive. If belt tension is too low, the belt will slip with resulting power loss and increased wear on the belt and associated sheaves.
As stated, the invention allows belt tension for a given belt size and power transmitting application to be held much more uniform or constant than in the prior art.
Other features and advantages of the invention will become apparent during the course of the following description.